PROC. ENT. SOC. WASH., VOL. 23, NO. 6, JUNE, 1921 147 



certain Geometridae); hollow flattened structures of various and diverse shapes 

 subject to extravagant modification; usually symmetrical but not seldom as- 

 symetrical (ex. many Gelechiidae, Gracilariidae, some Oecophoriidae). In most 

 forms three distinct areas can be differentiated: a costal, an apical and a dorsal. 

 These are sometimes defined by actual sutures (as in Ethmidae) indicating that 

 the harpes are compound organs (modified pedal appendages). More often 

 the areas are only defined by heavier chitimzation, or inward folding of the 

 edges, or by peculiarities of armature and hairs. These parts have been named 

 respectively, costa (Ca), cucullus (Cs) anil sacculus (Sc) (Pierce) which terms 

 we have-adopted. They are each subject to various modifications, and one is 

 often developed at the expense of the others; the sacculus and costa having a 

 tendency to develop into free extended arms. Occasionally one of these is so 

 far separated from the rest of the harpes as to form a double harpe structure 

 (Comp. Fig. 4). The so-called clasper of Smith prominently developed in the 

 Noctuidae\s a similar modification of the sacculus, being a free extension from 

 the edge near the base. It takes various shapes in different families, is often 

 forked and otherwise highly modified (ex. Agrotinae, Pyraustinae), and some- 

 times is represented by a mere thorn-like projection (ex. Epiblema, in Olethreu- 

 tidae}. Very often it is entirely absent. Similar clasper-like processes (Arl 

 may often be found arising from the annellus (ex. Ethmiidae, Stenomidae) and 

 sometimes fusing into the harpes. These must not be confounded with the 

 clasper of the harpes. All ot these characters are constant within the species, 

 and furnish excellent aid in the separation of higher groups. In a few groups 

 the harpes are greatly reduced and hardly capable of functioning as clasp- 

 ing organs. 



Transtilla (Ts). 



The transtilla is a more or less band-like bridge connecting the harpes at their 

 inner costal angles. Often merely a plain band. Often lobed or sinuated and 

 ornamented with spine clusters. Sometimes attenuated or broken in the mid- 

 dle (ex. Adoxophyes) and appearing as free arms from the harpes. These arms 

 may be reduced to mere knobs or spurs (ex. Oletkreutidae and a few Tortricidae). 

 Sometimes the transtilla is entirely absent (ex. Oecophoridae, Blastobasidae and 

 Noctuidae). 



Uncus (II). 



This and the following two structures constitute the armature of the anus 

 and therefore belongs to the 10th segment. The uncus is the posterior dorsal 

 projections of the genitalia above the anal opening. It is normally more or less 

 hook like (ex. Sparganothis^ bur may be broadened out (ex. Ge/echia), spoon 

 shaped (ex. Pandemis), tritid !e\. Ethmia zelleriellti), bifurcate (ex. Rhopob 

 or otherwise modified. It may he smoothed or haired. Often it is reduced or 

 absent. 



Socii (.Si). 



The socii are paired organs, normally soft, membranous and hairy; arising 

 from the base of the uncus, more or less lateral to the anal opening. The\ are 

 of very varied shape; commonly soft, papilla like and drooping (ex. EHCOSHHD, 

 sometimes erect (ex. Harpypteryx) or flattened or leaf-like (ex. SparganotAis), 



